1. Technical Field
The present invention relates generally to a liquid ejecting apparatus such as an ink jet type printer and a control method thereof, and more particularly to a liquid ejecting apparatus having a heater that heats an ejection target, and a control method thereof.
2. Related Art
A typical liquid ejecting apparatus has a liquid ejecting head with nozzles operable to eject various liquids. For example, an image recording apparatus, such as an ink jet type printer (hereinafter simply referred to as a printer) having an ink jet type recording head (hereinafter simply referred to as a recording head, and can also be referred to as a liquid ejecting head, which ejects ink in the form of a liquid) that records an image or the like by ejecting and landing ink in the form of liquid from nozzles of the recording head onto a recording medium (impact target) such as recording paper, can be given as a representative example of the liquid ejecting apparatus. Liquid ejecting apparatus are not limited to image recording. For example, in recent years, liquid ejecting apparatus have also been used in manufacturing, such as in manufacturing of a color filter of a liquid crystal display or the like.
Recently, printers have been used to perform printing on recording medium larger than the printing paper typically used in a general home printer, for example, an outdoor advertisement or the like. As the recording medium in this case, a resin film which is made of, for example, vinyl chloride can be used to provide weather resistance. A solvent ink containing an organic solvent as its main component can be used to print on such a resin film. The solvent ink has excellent scratch resistance and weather resistance compared to water-based ink.
Incidentally, since it is hard for the resin film to absorb ink, there is concern that a recorded image may bleed. In order to cope with such a problem, the use of a heater (a platen heater) to heat a recording medium on a platen has been proposed, in which the drying and fixing of ink landed on recording paper are promoted by heating of the recording paper by the heater (refer to JP-A-2010-30313, for example).
In the case of printing an advertisement or the like that is even larger than the maximum size of a recording medium capable of being printed by a printer, the advertisement can be partially printed on a roll-shaped film, the film cut and divided after printing into respective parts, and the respective parts can be joined together, thereby creating one sheet of continuous finished product. When, however, a recording medium is heated by the above-described heater, heat from the heater is transmitted to a recording head, whereby the viscosity of ink changes with time. In general, an increase in temperature of the inside of the recording head lowers the viscosity of the ink. If the viscosity of ink is lowered, the amount (weight or volume) of ink ejected at a given pressure is increased. That is, ejection characteristics change in accordance with the temperature. Accordingly, there is concern that the density of an image printed on the film may vary undesirably. As described above, where respective printed parts of an image are joined into one sheet, there is a problem where a difference in density is conspicuous at a boundary portion, thereby resulting in poor image quality. And when the temperature of the recording head is low at the start of the printing relative to the steady state temperature of the recording head, the resulting temperature change can easily cause the above-mentioned problem.